The Electroencephalogram in Subdural Hematoma

Abstract

T HE PATHOLOGY and treatment of subdural hematoma is well understood but the clinical picture is subject to great variance. The writers are impressed, both in clinical experience and in the review of the literature, by the difficulty with which an early diagnosis is madeJ ,6 Most publications on subdural hematoma are prefaced by statements that emphasize the inconsistent symptomatology and difficulty in diagnosis. I t is the attitude of some surgeons that whenever subdural hematoma is suspected a simple and expedient method of proof is to perform bilateral trephines. 3 With such a routine the percentage of negative explorations increases. I t is desirable to place the trephine openings in only those patients having a surgical lesion. This feeling gains added strength since trephine openings have an implication in the patient's industrial, insurance and psychic future. For these reasons additional diagnostic procedures have been employed. Pneumoencephalography is not without risk and is considered contraindicated by some authorities. 9 In the study of subdural hematoma, as in all neurological disease, diagnostic tests have been directed mainly toward disturbances of anatomical relations. With the confirmation of Berger's observation that the electrical activity of the brain followed a certain rhythmical pattern, and that in pathological states this fundamental pattern was altered, a useful diagnostic aid was placed in the hands of the clinician. The electroencephalograph offers a new and different approach in that alteration in the physiologic (electric) activity of the brain can be studied directly as well as indirectly. With subdural hematoma the abnormalities in electrical activity of the brain are shown to be altered dependent on: (1) the amount of the bleeding, (~) the location, and (3) the time interval between the bleeding and the EEG. There are reported in the literature several clinical and experimental observations on the EEG in subdural clot that appear conflicting. The EEG has been described as showing (1) increased voltage and slow wave pattern